ServiceGuard Extension for RAC

[No idea what I'm doing]

Hey, guys. I am going to ask a stupid question.

What is the purpose of having the ServiceGuard Extension for RAC? It seems to me that you already have your high availability provided by the RAC itself. RAC allows you to run several nodes on a shared database. If you lose one node, the others keep on keepin' on.

What additional benefits does SGeRAC provide?

Thank you.

[Steven E. Protter · Accepted solution]

Shalom,

The purpose of the software is to provide a set of package control scripts and cluster configuration designed to work with Oracle RAC.

This is work you could do yourself, but it would take a substantial amount of time.

RAC permits active-active clustering, which lets you have two or more database servers actively handling database connections to the same data, sitting on shared storage.

RAC versions after version 10 come with Oracle's clustering software which can work without the benefit of ServiceGuard. SG extension for RAC provides little additional benefit, but it can manage such issues as volume group activation and correctly rebooting nodes in the event of the cluster getting into trouble.

SEP

[Emil Velez]

1. if you configure RAC to use SLVM RAC provides the vgchange -a s feature

2. The GMS process (group membership services) is a process that is provided by that additional product that oracle ties into to determine group membership.

3. A set of sample scripts to start and stop the instance.

These this are provided by the SGERac add on to serviceguard.

[Thomas J. Harrold]

(on soapbox)

RAC is recycled TruCluster. On top of that, Oracle broke a few things. ServiceGuard is a much more robust clustering package.

(now back to the topic)

RAC will only handle the Oracle components, and it is NOT supported by Oracle to use RAC to control your application.

The RAC toolkit provided by SG Extentions for RAC make the deployment and management a bit easier. There is also a great SG/RAC whitepaper/cookbook out there. It fills in a few of the gaps from the Oracle documentation.

[Thomas J. Harrold]

Forgot to mention: if you do not have a 3rd party application that you need to control via the cluster, then you can survive without SG. (but I still wouldn't recommend it)

If you DO intend to run another app (non-oracle), then you MAY have to relax the default oracle permissions - Oracle provides a script to handle this in the install directory under $ORACLE_HOME.

Hope this helps.